Origin

Juston Seyfert was raised along with his younger brother Chris by his father, Pete, in Antigo, Wisconsin. His mother left their family when he was still very young because she tired of domestic life and responsibility. The Seyfert family lived in a junkyard Seyfert Salvage. Juston and Chris had a very close relationship, and frequently worked together to built battlebots. Unfortunately, Juston and his friends Matt and Alex, small for their age, were often picked on at school[2]

Juston first meets his Sentinel

Sentinel

When Juston discovered a control chip, he didn't realize how important the discovery really was and inadvertently activated the self-repair mode of a deactivated Sentinel.[2] After discovering the semi-operational Sentinel, Juston began helping to rebuild and reprogram him.[3]

Juston fighting crime with his Sentinel

Juston's first major use of the Sentinel was to scare Greg and Josh, two bully-jocks who had been tormenting him and his friends. It worked, and Juston appeared to be a hero for scaring off the Sentinel.[4] However, almost immediately after, Juston began to feel guilty for his ill-gotten fame. To redeem himself he began going out at night with the Sentinel to do some good including rescuing a truck driver from an accident[5] and rescuing four survivors of a lane crash.[6] Juston Sentinel was eventually caught by the Commission on Superhuman Activities, partially fearing being implicated and partially wanting to find his mother, Juston stole the Sentinel and ran away.[7][8]

Fearing that the reemergence of the Sentinel would lead to evidence of their assassination conspiracy, Colonel Hunt and Senator Knudesen decided to use a prototype Sentinel Mk VII-A to destroy the Sentinel and kill Juston.[9] Juston was not able to find his mother, but he was able to escape Hunt's Stealth Sentinel, rescue his family, and blackmail Hunt and Knudsen into leaving them alone. After the their final battle, Juston used parts from the deactivated Sentinel Mk VII-A to repair and enhance his Sentinel.[10]

Avengers Academy

After knowledge of Juston's Sentinel became public, everyone freaked out. To keep his Sentinel, Juston joined the Avengers Academy which had just expanded it's enrollment, and relocated to the Avengers Compound in Los Angeles, California.[11] Despite his father's protest, Juston chose to remain with the Avengers Academy.[12][13]

Juston continued to retool and modify his Sentinel, although it's presences at caused some issues with mutants at the Avengers Compound,[14][15][16][17] and despite his best efforts, Juston was unable to remove the "Destroy All Mutants" programming. Juston was able to add new directives that contradicted this original programming and set the "Destroy All Mutants" program as it's least important directive.[18]

When the Phoenix Force imbued five X-Men with its cosmic powers,[19] the Phoenix Five set out to reframe the world to their liking including the destruction of all Sentinels.[19]Emma Frost personally came to the Avengers Compound to destroy Juston's Sentinel.[18] Juston and the other students protested, and in the end Juston's Sentinel sacrificed itself to safe Juston from Emma. Luckily, Quicksliver was able to obtain the Sentinel's central processing unit before Emma destroyed it, but the Sentinel was able to be rebuilt.[12]

Avengers Arena

Juston and his Sentinel are among the sixteen young superheroes kidnapped by Arcade to battle to the death in his new Murderworld.[20] To prevent suspicion, Arcade sends a humanoid robot to live with his family in Antigo.[13]

Originally, Juston journeys out with his classmates X-23, Hazmat, and Reptil.[21] Unfortunately, it isn't long before Juston and his Sentinel are attacked by Apex.[1] During the struggle, Juston is paralyzed, the Sentinel destroyed, and Juston is left for dead among the Sentinel wreckage in the desert.[1][22]

Fortunately, Juston survives, and driven by revenge he rebuilds the Sentinel as a pilot operated fighting machine. Bent on revenge, Juston tries to kill Apex, but is stopped by Tim Bashir.[22] It isn't long however until Apex regains control of her shared body, snaps Juston's neck, and leaves with his Sentinel, Death Locket, and Chasehawk.[23] What remained of the Sentinel is finally destroyed by Nico with her Staff of One during her final battle with Apex.[24]